1. Field of the Invention
The present invention is related to devices for separating gaseous solutions or mixtures and, more particularly, to an apparatus for separating droplets and/or solid particles from a gas.
2. Description of the Related Art
Water, fibers or other such particles have commonly been separated from gas, particularly in connection with exhaust air of a paper machine wire section ventilation system, by using cyclone-type separators. A drawback of such separators is their great dimensional size when air flow is for example 10-30 m.sup.3 /s. Additionally, great pressure losses of cyclones and also their weak ability to separate the lightest particles or water mist has been experienced as a problem.
Another known way has been to provide an exhaust duct with so called vortex-separators, of which an example is shown in U.S. Pat. No. 4,014,673. In the solution according to that, fixed vanes impart rotating movement to the flowing air, whereupon particles flowing along the air are thrown into side walls of the device. Pressure loss required for accomplishing adequate centrifugal forces is a disadvantage in operation of this device also. In such devices, where only simple vanes are used, small particles moving near the center of the device do not have time to reach the side walls of the device before leaving it, whereupon the degree of separation remains unsatifactory.
In the solution shown in Finnish patent document 28784, the requirement for gas and collected water to move into different directions in an exhaust duct causes problems. In order to operate reliably, this solution calls for an extremely large diameter of the shell for reducing air velocity to a level, in which formed droplets do not follow the air flow anymore. Additionally, the device must be in a certain position in order to function at all.
In the solution shown in Finnish patent document 89562, the exhaust air is forced to make a change in flow direction, which in case high velocities are in question means always exess pressure losses and consumption of power. Additionally the construction requires a great deal of space.
In DE 3438400 there is shown circularly placed, specially formed plates for separating droplets. The plates are intended to change the direction of air flow and thus cause suitable impact and collect surface for the droplets. In this kind of solution problems may arise if the air contains also other impurities than liquid and if air velocity changes.
It is an intention of the present invention to provide an apparatus which minimizes the problems of prior art.